Improving Software Effort Estimation by Adjusting for Over-Commitment

Software Effort Estimation (SEE) is an important component of software project planning. Many projects fail due to inaccurate software estimates. Over-commitment is considered one of the factors that contribute towards inaccurate estimates. This study presents a mechanism to adjust software effort estimates for over-commitment. At step 1, the study identifies - through a pilot study and literature review- the factors that affect the SEE. A list of 43 factors affecting SEE is prepared from the existing literature and the pilot study. Then an industrial survey (Survey I) is conducted to know the extent to which each of these factors can affect the effort estimates. Results of the survey show that the most crucial factors affecting the SEE are over promising and over-commitment. At step 2, the study presents an approach to adjust existing effort estimates for over-commitment. These adjustments are proposed based on the Survey II results. The Survey II indicates the total percentage of effort estimates that are affected by over commitments as well as ten factors of over commitments. At step 3, the study validates the proposed adjustment approach through an experimental survey (Survey III); around 77.08^% of the respondents considered the adjustments good. During the validation step, we collected information regarding the estimated and the actual effort spent. The results of the evaluation show that on average, the effort estimates were off by 20.24%. After applying the proposed adjustments this percentage was reduced to 17.99% on average. This reduction indicates that the proposed adjustments have improved the accuracy of the effort estimates by 11.12% approximately. The fact that 17.99% estimates are still inaccurate indicates there is still a need to have more adjustment factors for SEE.